[#4604] Add basic caching for TimeEntry#cost

db/migrate/004_add_cost_to_time_entries.rb

@@ -0,0 +1,9 @@
+class AddCostToTimeEntries < ActiveRecord::Migration
+  def self.up
+    add_column :time_entries, :cost, :decimal, :precision => 15, :scale => 2
+  end
+
+  def self.down
+    remove_column :time_entries, :cost
+  end
+end

lib/rate_time_entry_patch.rb

@@ -20,15 +20,28 @@ module RateTimeEntryPatch
   module InstanceMethods
     # Returns the current cost of the TimeEntry based on it's rate and hours
     def cost
-      if self.rate.nil?
+      unless @cost
-        amount = Rate.amount_for(self.user, self.project, self.spent_on.to_s)
+        if self.rate.nil?
-      else
+          amount = Rate.amount_for(self.user, self.project, self.spent_on.to_s)
-        amount = rate.amount
+        else
+          amount = rate.amount
+        end
+
+        if amount.nil?
+          @cost = 0.0
+        else
+          @cost = amount.to_f * hours.to_f
+        end
+        
+        cache_cost
       end
 
-      return 0.0 if amount.nil?
+      @cost
-      
+    end
-      return amount.to_f * hours.to_f
+    
+    def cache_cost
+      @cost ||= cost
+      update_attribute(:cost, @cost)
     end
   end
 end

test/unit/lib/rate_time_entry_patch_test.rb

@@ -5,7 +5,7 @@ class RateTimeEntryPatchTest < ActiveSupport::TestCase
     @user = User.generate!
     @project = Project.generate!
     @date = Date.today.to_s
-    @time_entry = TimeEntry.new({:user => @user, :project => @project, :spent_on => @date, :hours => 10.0})
+    @time_entry = TimeEntry.new({:user => @user, :project => @project, :spent_on => @date, :hours => 10.0, :activity => TimeEntryActivity.generate!})
   end
   
   should 'should return 0.0 if there are no rates for the user' do
@@ -26,4 +26,40 @@ class RateTimeEntryPatchTest < ActiveSupport::TestCase
 
   end
 
+  context "#cost" do
+    setup do
+      @time_entry.save!
+      Rate.generate!(:user => @user, :project => @project, :date_in_effect => @date, :amount => 200.0)
+    end
+    
+    context "without a cache" do
+      should "return the calculated cost" do
+        @time_entry.update_attribute(:cost, nil)
+        assert_equal 2000.0, @time_entry.cost
+      end
+      
+      should "cache the cost to the field" do
+        @time_entry.update_attribute(:cost, nil)
+        @time_entry.cost
+
+        assert_equal 2000.0, @time_entry.read_attribute(:cost)
+        assert_equal 2000.0, @time_entry.reload.read_attribute(:cost)
+      end
+      
+    end
+
+    context "with a cache" do
+      setup do
+        @time_entry.cache_cost
+      end
+      
+      should "return the cached cost" do
+        assert_equal 2000.0, @time_entry.read_attribute(:cost)
+        assert_equal 2000.0, @time_entry.cost
+      end
+      
+    end
+
+  end
+
 end